This invention relates to improvements in traffic light signals operative to inform the driver of an on-coming vehicle that he is permitted to make a turn on red-signal after coming to a full stop at that intersection, and to inform him in which direction transversely of his present course he is permitted to make such a turn.
At the present time, turns to the right after making a full stop are permitted during a red stop light interval at most controlled intersections, but at each intersection the driver must carefully look to see if a "no turn on red" sign has been posted. These signs are hung in a confusing diversity of locations and are easily missed by drivers who already have many other traffic conditions to watch.
It is the purpose of this invention to eliminate the need for "no turn on red" signs, and eventally to have all intersections entirely controlled by stop lights in such a way that a continuous red light unequivocally means "stop and remain stopped", and it is the further purpose of the invention to have the lens indications on stop lights show permission to turn after a full stop where such turns are permissible, thereby eliminating the burden of requiring a motorist to find at his peril whether a "no turn on red" sign has been posted somewhere in the vicinity.
U.S. Pat. No. 2,219,092 to Z. L. Hoover seeks to accomplish a similar purpose by modifying sectors or segments of traffic light lens and/or selectively illuminating these sectors when a turn is permitted. The altered sectors are selectively illuminated in an unflashing manner at moments when the turn is permitted or left dark at moments when it is not permitted. This disclosure, therefore, is intended to replace the separate arrow light-signal pointing right or left, rather than to permit removal of "no turn on red" signs at those intersections where a turn on red is not permitted. In FIGS. 4, 5 and 6 of that patent where the main lens is red, a turn to one side or the other is signalled by selective illumination of a green insert in the lens when the lamp behind the insert is energized. The problem with this type of indication is that sharp vision is required to distinguish a small green insert in a larger red field, especially where overhead suspended lights are seen against a bright blue sky. The visual perception problem is aggravated not only by the smallness of the insert but also by the change of color. Many people whose vision is marginal drive vehicles, and therefore the traffic signals must be very clear and not easily mis-read by the motorist